The present invention relates to wafer charge reduction systems for ion implanters, and to so-called electron flood guns for introducing negative charge into the ion beam to reduce positive charging of ion implanted wafers. In particular, the invention relates to an electron flood gun and to methods of operation which provide a hitherto unattainable combination of large magnitude flood electron current and low energy characteristics which are required to control or eliminate both local and bulk positive charging by the ion implant beam.